Aeroflex 3920 freq shifts with mic on

[dag]

I hope this is easily remedied. I found that my 3920 generator frequency will shift up nearly 4Khz when I simply turn on EX using the Mic input. It does not matter if anything is even connected to the mic jack, just having the phantom voltage there is enough. This tells me there is no DC blocking on the mic port.

Any ideas?

[nukedude]

My work had two Aeroflex 3500A test sets that would do that as well. They would also drift when testing radios. Sometimes they would get stuck in Transmit test and would not change to Receiver test. A manufacturing defect was found in both units, they tried to charge us for the repair, and eventually fixed them and shipped them back to us. (We had 14 units and two were acting up.)

You may be able to post on some test equipment sites and see if this is common for the 3920's.

[Wowbagger]

I talked to the project lead - the issue is the phantom power (for electret microphones) is offsetting the voltage. If you turn on phantom power and leave it on for a long time, the capacitor will eventually block the signal and you should be OK.

[dag]

Thanks. I will give this a try.

I talked to the project lead - the issue is the phantom power (for electret microphones) is offsetting the voltage. If you turn on phantom power and leave it on for a long time, the capacitor will eventually block the signal and you should be OK.

[pasbanfsd001]

I hope this is easily remedied. I found that my 3920 generator frequency will shift up nearly 4Khz when I simply turn on EX using the Mic input. It does not matter if anything is even connected to the mic jack, just having the phantom voltage there is enough. This tells me there is no DC blocking on the mic port.

Any ideas?

_____________

Farasat